Microbial Diseases of the Digestive System

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

PowerPoint® Lecture Slide Presentation prepared by Christine L. Case

M I C R O B I O L O G Ya n i n t r o d u c t i o n

ninth edition TORTORA FUNKE CASE

Part B25Microbial Diseases

of the Digestive System


Escherichia coli Gastroenteritis

Occurs as traveler's diarrhea and epidemic diarrhea in

nurseries.

50% of feedlot cattle may have enterohemorrhagic

strains in their intestines.

Enterohemorrhagic strains such as E. coli O157:H7

produce Shiga toxin.

O = cell wall antigen

H = flagellar antigen


Campylobacter Gastroenteritis

Campylobacter jejuni Usually transmitted in cow's milk


Helicobacter Peptic Ulcer Disease

Treated with antibiotics

H. pylori causes stomach

cancer

Figure 11.12


Helicobacter Peptic Ulcer Disease

Figure 25.14


Yersinia Gastroenteritis

Y. enterocolitica and Y. pseudotuberculosis Can reproduce at 4°C

Usually transmitted in meat and milk


Clostridium Infections

Clostridium perfringens Gastroenteritis

Grow in intestinal tract, producing exotoxin

Clostridium difficile–associated diarrhea

Grow following antibiotic therapy

Associated with hospitalized patients and nursing

home residents


Bacillus cereus Gastroenteritis

Ingestion of bacterial exotoxin produces mild

symptoms.


Mumps

Mumps virus

Enters through

respiratory tract

Infects parotid glands

Prevented with MMR

vaccine

Figure 25.15


Hepatitis

Inflammation of the liver.

Hepatitis may result from drug or chemical toxicity, EB

virus, CMV, or the hepatitis viruses.


Transmission Causative agent Chronic liver disease?

Vaccine?

Hepatitis A Fecal-oral Picornaviridae No Inactivated virus

Hepatitis B Parenteral, STD

Hepadnaviridae Yes Recombinant

Hepatitis C Parenteral Filoviridae Yes No

Hepatitis D Pareteral, HBV coinfection

Deltaviridae Yes HBV vaccine

Hepatitis E Fecal-oral Caliciviridae No No

Hepatitis


Hepatitis B Virus

Figure 25.16

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 25.17

Viral Gastroenteritis

Rotavirus: 3 million cases annually 1-2 day incubation; 1 week illness

Norovirus: 50% of U.S. adults have

antibodies 1-2 day incubation; 1-3 day

illness Treated with rehydration


Mycotoxins

Mycotoxins are produced by some fungi Claviceps purpurea

Grows on grains Produces ergot

Toxin restricts blood flow to limbs; causes

hallucination Aspergillus flavus

Grows on grains Produces aflatoxin

Toxin causes liver damage; liver cancer


Giardiasis

Giardia lamblia Transmitted by

contaminated water

Diagnosed by

microscopic examination

of stool for ova and

trophozoite

Treated with

metronidazoleFigure 25.18


Cryptosporidiosis

Cryptosporidium hominis Transmitted by oocysts in

contaminated water

Diagnosed by acid-fast

staining of stool or

presence of antibodies by

FA or ELISA

Treated with oral

rehydrationFigure 25.19


Cyclospora Diarrheal Infection

Cyclospora cayetanensis Transmitted by oocysts in contaminated water

Diagnosed by microscopic examination for oocysts

Treated with trimethoprim and sulfamethoxazole


Amoebic Dysentery

Entamoeba histolytica Amoeba feeds on RBCs

and GI tract tissues

Diagnosis by observing

trophozoites in feces

Treated with

metronidazole

Figure 12.18b

Microbial Diseases of the Digestive System

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